The present invention relates to a transmission circuit which drives an ultrasonic transducer, an ultrasonic probe equipped with the transmission circuit, and an ultrasonic image display apparatus.
An ultrasonic image display apparatus transmits ultrasound to within a subject from an ultrasonic probe connected to an apparatus main body and receives its echoes through the ultrasonic probe thereby to generate an ultrasonic image within the subject. The ultrasonic probe is equipped with an ultrasonic transducer comprised of a piezoelectric material such as piezoelectric ceramic. The ultrasonic transducer is driven by a transmission circuit to perform the transmission of ultrasound (refer to, for example, Japanese Patent Application Laid-Open No. 2004-358133 and Japanese Patent Application Laid-Open No. 2008-68014). The transmission circuit is generally provided in the apparatus main body.
Now, a study of the provision of a transmission circuit in an ultrasonic probe is being conducted. When the transmission circuit is provided in the ultrasonic probe, it needs to be made smaller. Since the ultrasonic probe is held by an operator, the transmission circuit provided in the ultrasonic probe also needs to suppress the generation of heat due to power consumption rather than the case of the provision thereof in an apparatus main body.
It is however difficult for a conventional transmission circuit to be provided in an ultrasonic probe due to the size of the circuit and the generation of heat. For example, a transmission circuit described in JP 2004-358133, using complementary transistors and a ground clamp circuit, presents a problem in the generation of heat because power consumption is large upon generating coded pulses. There has also been known one using a Class-A amplifier as a transmission circuit. Since, however, the Class-A amplifier needs a feedback circuit, the size of the circuit becomes a problem. Further, since a high-speed feedback circuit becomes necessary, power consumption is large and the generation of heat also becomes a problem.